This is not yet another thread to compare your MPG.
I want a checklist of items to inspect if someone is suddenly getting 6mpg.
Huge tires are not on the list b/c this is not a mechanical failure.
Can we put this in the right order? Also, do you have anything to add?

Top causes of sudden poor gas mileage

1. Correct tire air pressure
2. Pre-cat O2 sensor (This seems like the #1 mechanical defect that causes sudden loss of mpg)
3. General tune up: Plugs, wires, cap, rotor
4. Cracked exhaust manifold
5. MAP Sensor
6. Coolant temp sensor?
7. Plugged Cat?
8. Clean throttle body
9. Fuel filter?
10. Seized hub bearings / u-joints?

 

you forgot THE #-1 of them all.......

DRIVING A JEEP (.)

 

General tune up oughta be #1.
A dirty fuel filter will not cause poor mileage.
Seized hub bearings/u-joints seems like a stretch to me.

 

In-town driving
Excessive hiway speed


In fact, my 97 gets it's best mpg at around 55 mph.

 

I get 18 around town..not sure about highway..i have the factory console that tells MPG and distance to empty

 

havent heard anything about the coolant temp sensor. can anyone elaborate on that?

 

hahaha That was my first thought when I saw the post!

 

For Highway Driving:
1) Tune Up
2) Cruising speed - once you start going over 65 mph...your MPGs will drop significantly
3) Tires/Lift --- more is less (MPG)
4) External accessories (roof racks, tire carriers, light bars, aftermarket bumpers)
5) Gearing

 

This! I get horrible gas mileage around town, about 10mpg. I live right down town SLC, so to go anywhere it's constant stop and go at stop lights. If I get out on the freeway, I get around 22-25 mpg.

 

great minds think alike...

 

Tire Pressure low -> low MPG